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1. Refer to the diagram side view-which shows a rigid structure consisting aris

ID: 3161484 • Letter: 1

Question

1. Refer to the diagram side view-which shows a rigid structure consisting aris of three massless rods and three point masses, hanging initially at rest from a frictionless stationary pin located at mass A. (In other words: The structure is free to rotate but only around the pin and only in the plane of the paper) Then a steady torque of 267 N.m is applied around the pin in a counter- clockwise direction, until the entire structure has rotated by 134 At that point, the torque is removed entirely. The following questions assume the torque has already been removed. Neglect all air drag and friction, and assume g 9.80 m/s a. Find the maximum speed of the structure's center of mass. b. Find the net force acting on mass B when rod BC is moving directly (vertically) upward. 2 kg 3 m. 4 kg mc, 4 kg ground)

Explanation / Answer

When BC rod is moving vertically upwards, the line connecting centre of the BC rod and mass A is making an angle of 90 degree with the vertical.

Total energy in the system is torque * angle = 267* 134/180 pi

That is 624.4439 Nm

Now height of centre of mass is that length of the same connecting line which is 3.09 m

Hence velocity can be found by noting

Kinetic energy = total energy - potential energy

1/2mv2   = 624.4439 - 8(9.80)3.09

Using this v find mv2/r for mass B and substract mg from that will give you net force.